perf/core: Export AUX buffer helpers to modules

Perf PMU drivers using AUX buffers cannot be built as modules unless
the AUX helpers are exported.

This patch exports perf_aux_output_{begin,end,skip} and perf_get_aux to
modules.

Cc: Peter Zijlstra <peterz@infradead.org>
Signed-off-by: Will Deacon <will.deacon@arm.com>

kernel/events/ring_buffer.c

@@ -411,6 +411,7 @@ err:
 
 	return NULL;
 }
+EXPORT_SYMBOL_GPL(perf_aux_output_begin);
 
 static bool __always_inline rb_need_aux_wakeup(struct ring_buffer *rb)
 {
@@ -480,6 +481,7 @@ void perf_aux_output_end(struct perf_output_handle *handle, unsigned long size)
 	rb_free_aux(rb);
 	ring_buffer_put(rb);
 }
+EXPORT_SYMBOL_GPL(perf_aux_output_end);
 
 /*
  * Skip over a given number of bytes in the AUX buffer, due to, for example,
@@ -505,6 +507,7 @@ int perf_aux_output_skip(struct perf_output_handle *handle, unsigned long size)
 
 	return 0;
 }
+EXPORT_SYMBOL_GPL(perf_aux_output_skip);
 
 void *perf_get_aux(struct perf_output_handle *handle)
 {
@@ -514,6 +517,7 @@ void *perf_get_aux(struct perf_output_handle *handle)
 
 	return handle->rb->aux_priv;
 }
+EXPORT_SYMBOL_GPL(perf_get_aux);
 
 #define PERF_AUX_GFP	(GFP_KERNEL | __GFP_ZERO | __GFP_NOWARN | __GFP_NORETRY)